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- 21 - <br />discharges from the Entrada Sandstone, and Spring No. 10 discharges <br />from the Salt Wash Member of the Morrison Formation. <br />The hydrologic properties of the geologic materials in the region <br />are summarized on Table IV and on 3. The positions of potential <br />aquifers in the regional structural setting are shown on Fig. 5. Some <br />surficial deposits and several bedrock formations are expected to have <br />moderate to high hydraulic conductivities and are potential aquifers <br />when below the water table. These potential aquifers are: <br />(1) Alluvium and leached Paradox caprock. <br />(2) Dakota Sandstone and Burro Canyon Formation. <br />(3) Slick Rock Member of the Entrada Sandstone. <br />( Limestone Member of the Hermosa Formation. <br />(5) Older Paleozoic rocks. <br />Studies done by Konikow and Bedinger (1978) indicate that the alluvium <br />below the Paradox Valley floor and the underlying gypsum and anhydrite <br />caprock are moderately to highly permeable. This zone of relatively <br />high permeability extends to depths of 500 to 1,500 feet below the <br />valley floor, Hite and Lohman (1973). At these depths, the underlying <br />evaporite rocks are expected to have extremely low hydraulic <br />conductivity as a result of plastic flowage and confining stresses. <br />The high permeability in the upper evaporite beds is the result of <br />near surface fracturing and leaching of salts in the caprock. <br />Ground water in the upper unconfined valley aquifer system flows <br />towards and discharges into the Dolores River. The majority of ground <br />water in the valley aquifer system southeast of the river are brines. <br />- However, it is believed that in places, thin lenses of fresh water may <br />